1. Field of the Invention
This invention relates to a motor vehicle keyless entry system and an encoded marker used therein; and more particularly, to a keyless entry system that provides a driver, bearing a personally encoded marker, convenient, reliable and quick access to the vehicle's interior.
2. Description of the Prior Art
Keyless entry systems, upon which this invention has improved, are conventionally employed as convenience items with the additional capability of enhanced theft protection. There presently exists three main classes of such keyless entry systems including an infrared system, a radio frequency system and an electronic combination pad.
The infrared system consists of a hand held source module and an infrared sensing and decoder module mounted on the vehicle. When the hand held source module is activated and correctly aimed at the sensor decoder, the frequency or pulse modulated code from the source module is decoded and compared to a preprogrammed code. If both codes match, the door lock mechanism is electronically disengaged allowing entry to the vehicle's interior. This system has several faults, the most problemsome of which is presented by the difficulty encountered by the user in attempting to physically activate the source module while his hands are full or restricted. Once activated, the source module must be correctly aimed, making sure there are no obstructions between the source and sensing module. In foul weather and/or in dimly lit areas, the difficulties of aiming the source module and avoiding obstructions between it and the sensing module are readily apparent. Such obstructions are oftentimes present as snow, dirt, ice and the like. Additionally, in bright light, the sensing module may be incapable of sensing the source module. Yet another fault is presented by the requirement that each of the source and sensing modules have an individual power supply, thereby reducing the reliability of the system.
The radio frequency (RF) system consists of a hand held source module and an RF receiver and decoder mounted on the automobile. The RF system is similar to the infrared system in that the source module must be physically activated; however, the RF source module need not be aimed. When the source module is activated, the receiver transmits the coded RF signal to the decoder. Upon verification of the coded RF signal, the door lock mechanism is disengaged, allowing access to the vehicle's interior. The RF system has disadantages similar to the infrared system in that the source module must be physically activated (a task made difficult when the user is wearing gloves) and requires its own power source. Still another drawback of the RF system is the tendency of RF interference, generated by motors, radio communicating devices or electrical storms which may jam the receiver or generate false signals that inadvertently disable the lock engaging mechanism.
The third class of keyless entry systems is the electronic combination pad. The electronic combination pad consists of a panel of approximately five buttons (keys) located in the vicinity of the door handle on the automobile. Each of these buttons are usually marked with different symbols. Alternately, the order of a geometric pattern serves the same purpose. When access to the vehicle's interior is desired, the depression of these buttons in a predefined sequence disengages the door locks. One of the disadvantages of the electronic combination pad is presented by the requirement that the buttons be physically activated or depressed. This task is made difficult (1) when the user is wearing gloves, (2) when the keys are obstructed by snow, dirt or ice and (3) when the keypad must be operated in darkness or foul weather. Further, with electronic combination pads, there is a chance that the sequence or combination may be forgotten. As a result, keyless entry systems, though available as options in certain vehicles, have heretofore not gained widespread acceptance by vehicle manufacturers and consumers.